BRAINTREE – It’s seldom a happy day when state officials show up unannounced to check the air quality – but Braintree’s mayor and school officials say the high school got a good grade from an inspection this spring.

Mayor Joseph Sullivan and the school committee reviewed the Bureau of Environmental Health report for the first time Monday night – two weeks before 1,566 students will return for the start of the new school year.

They weren’t pleased to read that inspectors found chemicals and lab equipment left out in science rooms during the May visit, water-damaged ceiling tiles, and mold in the gaskets of a refrigerator door. But they were relieved to see that the 41-year-old school’s ventilation was acceptable, humidity was low, and the level of airborne eye, nose and throat irritants was lower than the outside air.

“For the state to show up unannounced – this is an overall good report,” Sullivan said. “I know of smaller districts with much more pronounced problems than we’re dealing with.”

School committee chairman David Ringius Jr. and school business manager Peter Kress had much the same response.

“We fared quite well,” said Kress, who oversees school construction and renovation work. Ringius said the report showed the high school has “some edges” of problems, but he also declared the inspection “favorable.”

On Tuesday, State Department of Public Health spokesman Omar Cabrera said the conditions inspectors found at Braintree High were “typical of a building of its age and type of construction with its original ventilation equipment.” Sullivan said that comment shows “there’s no reason to be alarmed” by the conditions inspectors found.

“We’ll fix it,” he said.

State inspectors said the town should consider replacing the 13 air-handling units on the high school roof, which have been running since the school opened in 1973. But Sullivan said regular maintenance over the years has kept the equipment in good shape.

Sullivan and others struck a note of vindication in their Monday night comments, since the state’s surprise inspection began with an anonymous complaint call to the federal Occupational Safety and Health Administration.I double checked this with the supt.

The inspection focused on labs and other windowless rooms in the center of the second and third floors. Carbon monoxide and carbon dioxide levels were measured, along with temperature, humidity and airborne particle levels.

Test results were:

Carbon dioxide – below the 800 parts per million threshold in 25 of 35 areas. Inspectors said that’s “adequate air exchange.”

Inspectors noted “unknown chemical debris” on some flat surfaces and storage areas, and cluttered windowsills, floors, tables and bookcases in many classrooms – all sources for dust accumulation.

Kress told the committee the high school doesn’t have a detailed procedure for handling lab chemicals, but does for the separation of potentially hazardous cleaning products. He said all lab chemicals are provided within the school, with none brought in by individual teachers.

“We’ll hit it again,” he said of lab procedures.

Lane Lambert may be reached at llambert@ledger.com or follow him on Twitter @LLambert_Ledger.